1. Field of the Invention
The present invention relates to a coil bobbin for a transformer used, for example, in a large AV amplifier which is recently more used with the spread of DVD, more particularly, to a coil bobbin provided with a separate terminal board.
2. Description of the Related Art
A coil bobbin of this type is known as disclosed in Japanese Utility Model Application No. 56-118376 wherein a coil bobbin and a terminal board are separately formed, and the terminal board is mounted on a flange of the coil bobbin during assembly.
FIG. 13 is a perspective view of a flange portion of a coil bobbin 30 and a terminal board 31 to be mounted on the flange portion of the above described conventional example.
In this conventional example, through holes 33 for mounting the terminal board are formed at both ends of a terminal board mounting portion which is formed at an end of an upper flange 32 of the coil bobbin 30. Long arms 35 for mounting are formed at both ends of a lower surface of the terminal board 31 in which terminals 34 are implanted, and hooks 36 are formed on outsides of tips of the arms 35.
When the terminal board 31 is mounted on the terminal board mounting portion of the upper flange 32 of the coil bobbin 30, the arms 35 formed with the hooks 36 at their tips are inserted in the through holes 33 in the upper flange 32 so that the hooks 36 reach a lower side of the upper flange 32. The hooks 36 prevent the terminal board 31 from coming off and fix the terminal board 31 to the terminal board mounting portion of the upper flange 32.
The coil bobbin 30 of the conventional example has a problem that spaces where the through holes 33 for mounting the terminal board 31 are formed must be secured at both sides of the upper flange 32, thus leading to an increase in an outer dimension.
Further, there is a problem that the long arms 35 formed from molding on the terminal board 31 are apt to splinter.
The present invention is achieved in view of the above and has its object to provide a coil bobbin for a transformer wherein no through hole is formed in both sides of an upper flange to thereby prevent upsizing, no long arm apt to splinter is formed on a terminal board, the terminal board can be readily mounted to the flange, and even when the terminal board formed from the molding warps, the warp can be corrected by the mounting.
The present invention attains the above described object according to a configuration of a coil bobbin in which an end of an upper flange 3, 3A, 3B formed on an upper end of a drum 2, 2A, 2B is formed with a terminal board mounting portion 5, 5A, 5B, and in which a separately formed terminal board 8, 8A, 8B is mountable on the terminal board mounting portion 5, 5A, 5B, wherein an inside of the terminal board mounting portion 5, 5A, 5B is formed with a rib 7, whose upper portion is formed with a plurality of plate-like walls, and an inner end of the terminal board 8, 8A, 8B is formed with a plurality of through holes 17 in which the walls are inserted.
Another feature of the present invention is that an inner surface of the terminal board 8, 8A, 8B is formed with a projection 14 for engagement, and that the above described wall is formed with a through hole 9a or recess 9b to be engaged with the projection 14.
Still another feature of the present invention is that an inner end of the terminal board 8, 8A, 8B is formed with outer clipping tabs 16 placed on an outside of the rib 7 and a concavity 13 placed on an inside of the rib 7, such that the rib 7 is clipped between the outer clipping tabs 16 and the concavity 13.
Yet another feature of the present invention is that the inner end of the terminal board 8, 8A, 8B is formed with the outer clipping tabs 16 placed on the outside of the rib 7, the concavity 13 placed on the inside of the rib 7, and also formed with inner clipping tabs 15, and that the rib 7 is clipped therebetween.
Further feature of the present invention is that at least two reinforcing ribs 18, 18A are formed on an upper surface of the terminal board mounting portion 5.